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JSON Validator
Validate JSON syntax in the browser and find errors before using payloads in APIs.
Process the input to see the result here.
Validate JSON syntax to find quote, comma, brace, and bracket problems before using payloads in APIs, configs, or tests.
When to use
Use it when an API rejects a payload, a config file fails, or you need to confirm that a snippet is valid JSON.
Input
Paste JSON with double quotes and complete arrays or objects. Comments and trailing commas are not valid JSON.
Output
The output confirms valid JSON or returns an error message to guide the fix.
- Paste the JSON payload you need to check.
- Run validation and read the returned error if one appears.
- Fix commas, quotes, escapes, braces, or brackets.
- After validation, use JSON Formatter or JSON Minifier depending on the destination.
- API errors: Confirm whether a failure comes from invalid JSON before investigating business rules.
- Configuration files: Validate JSON config before copying it into a runtime environment.
- Test payloads: Check mocks and fixtures before using them in automated tests.
- No JSON Schema: The tool does not validate expected types, required fields, or business rules.
- Comments are invalid: Standard JSON does not allow // or /* */ comments; remove them before validating.
- Single quotes: JSON requires double quotes for strings and property names.
- Generic parser errors: Parse messages can vary by browser; isolate the issue with a smaller snippet when needed.
- JSON Formatting, Validation, and TypeScript Workflow
Move from unreadable JSON to validated payloads and TypeScript interfaces with a practical workflow for API responses and config files.
Validate an object
Input: {"ok":true}
Output: Valid JSON
Does the validator check syntax or business rules?
It checks JSON syntax only.
Does it validate JSON Schema?
No. Schema validation requires an additional specialized validator.
What is returned when JSON is valid?
It returns the message Valid JSON.
What happens when JSON is invalid?
It returns an error indicating malformed JSON syntax.
Is my JSON sent to an external service?
No. Validation is local in the browser.
How do I use this tool safely?
Use the tool as a short workflow: review the expected input, run processing, and validate the output: Fields: JSON (textarea, required). Example workflow: {"ok":true} -> Valid JSON. Enter the requested input, run the tool, and review validation messages or warnings before copying the result.
Which inputs and outputs should I check?
Check this tool's input fields, examples, and output before using the result: JSON (textarea, required). Use the fields, formats, and limits described in the tool interface; review the output before applying it to critical workflows.